Duct adaptor ring



FIG. 1 is a bottom perspective view of a duct adaptor ring showing ournew design;

FIG. 2 is a bottom view of the design of FIG. 1;

FIG. 3 is a side view of the design of FIG. 1; and,

FIG. 4 is a top view of the design of FIG. 1.

The ornamental design for a duct adaptor ring, as shown and described.